The present invention relates to a method and apparatus for wrapping a load with packaging material.
Loads have been stretch wrapped with stretch wrap packaging material by dispensing the packaging material, securing a leading end of the packaging material to the load or a turntable clamp, and providing relative rotation between the load and a packaging material dispenser to cause the load to be enveloped by the packaging material. The relative rotation can be provided several different ways. Either the load can be rotated on a turntable, or the dispenser can be rotated around the stationary load. Stretch wrapping usually employs a web of stretch film as the packaging material.
Semi-automatic stretch wrapping machinery requires the operator to attach a leading end of the packaging material to the load. This is typically accomplished by forming a rope in the leading end of the film and then inserting this end between the layers of the load or tying the end of the packaging material to the edge of the supporting wood pallet or any suitable outcropping on the load. This attachment must be relatively strong since it provides the resistance to pulling the film from the film dispenser during the initiation of the relative rotation between the load and the film dispenser. The attachment or tying of the film makes film removal more difficult after the load has been shipped to its destination.
Automatic stretch wrapping machines typically use film clamps that grip the film web between two opposed surfaces and use electrical or pneumatic actuators to open and close the clamps. Such film clamps create a "tenting" effect during wrapping due to the distance between the clamp and the load during wrapping, resulting in wasted film and loosely wrapped loads. Such clamps are expensive and may require costly maintenance for the electrical and mechanical actuators.
In light of these drawbacks, there is a need for a method and apparatus for wrapping a load with packaging material that operates as effectively as those previously developed but which can be manufactured at a lower cost.